The DE 3802684 A1 discloses a torque sensor for electric power steering with a torsion bar whose two ends are connected to the cylindrical sleeves, each of which surrounds about half of the torsion bar. Both sleeves carry at their mutually facing ends, each an annular neck, which is connected by flexible webs with a hollow cylindrical ring. Upon relative rotation of the two ends of the torsion bar, the latter ring is displaced in the axial direction, which is detected by the hollow-cylindrical ring associated sensor coils.
More generally speaking, a relative rotation of two portions of a shaft by means of a mechanical connection will be converted into an axial linear motion.
This general principle is also known in the following publications:
EP 2108932 A2 (U.S. Pat. No. 8,109,156 B2), in which an link guide is used,
U.S. Pat. No. 5,115,685 A, which shows a resiliently elastic element with deformable webs,
U.S. Pat. No. 2,260,036 with a link guide and coupling of a sensor element via coil springs,
U.S. Pat. No. 5,165,288, where a lever linkage moves a transmitter ring,
U.S. Pat. No. 4,907,461, wherein two annular discs are coupled together by springs,
U.S. Pat. No. 4,809,557 and U.S. Pat. No. 6,370,968, where again link guides be employed and finally
U.S. Pat. No. 6,854,322 and U.S. Pat. No. 5,353,684.
For the simultaneous measurement of torsion and rotation angle, it is known from EP 1426750 1 and U.S. Pat. No. 7,258,027 B2 to use gears, magnets and magnetic sensors.
The above-described sensors for simultaneous measurement of torsion and rotation angle are mechanically very complex.